As a typical main circuit configuration of an AC power converter that performs AC/AC conversion (hereinafter, such an AC power converter is simply referred to as “power converter”), an indirect power converter is generally used, which converts a commercial AC into a DC via a rectifier circuit and a smoothing circuit, and obtains an AC output by a voltage source inverter.
Meanwhile, as a mode of directly obtaining an AC output from an AC voltage, a mode using a direct power converter typified by a matrix converter is known. This eliminates a necessity to use large capacitors and reactors, which smooth voltage pulsation due to a commercial frequency, and accordingly, size reduction of the converter can be expected, and in recent years, this direct power converter has been drawing attention as a next-generation power converter.
For the direct power converter, a configuration with a DC link has also been proposed, and a configuration without a smoothing circuit in a DC link on an input side of an inverter and a principle of a modulation mode in the configuration are described in U.S. Pat. No. 6,995,992, Wei, L., Lipo, T. A., Chan, H, “Matrix Converter Topologies With Reduced Number of Switches,” PESC 2002, Jun. 23-27, 2002, vol. 1, pp 57-63 and L. Wei, T. A. Lipo, “Investigation of 9-switch Dual-bridge Matrix Converter Operating under Low Output Power Factor,” IEEE IAS2003, vol. 1, pp. 176-181. Here, with regard to the modulation mode, a method for generating a signal wave is described in detail; however, with regard to synchronization between the rectifier circuit and the inverter, FIG. 10 is only shown in Wei, L., Lipo, T. A., Chan, H, “Matrix Converter Topologies With Reduced Number of Switches,” PESC 2002, Jun. 23-27, 2002, vol. 1, pp 57-63, and FIG. 12 is only shown in Japanese Patent Application Laid-Open No. 2004-266972.
Moreover, Wei, L., Lipo, T. A., Chan, H, “Matrix Converter Topologies With Reduced Number of Switches,” PESC 2002, Jun. 23-27, 2002, vol. 1, pp 57-63 describes that a direct power converter with a DC link is controlled by using a DSP (Digital Signal Processor) and a CPLD (Complex Programmable Logic Device). However, details of logic adopted in the DSP and the CPLD are not disclosed.
Meanwhile, as a modulation mode similar to those of U.S. Pat. No. 6,995,992, Wei, L., Lipo, T. A., Chan, H, “Matrix Converter Topologies With Reduced Number of Switches,” PESC 2002, Jun. 23-27, 2002, vol. 1, pp 57-63 and L. Wei, T. A. Lipo, “Investigation of 9-switch Dual-bridge Matrix Converter Operating under Low Output Power Factor,” IEEE IAS2003, vol. 1, pp. 176-181, a modified symmetrical triangular wave mode is shown in Japanese Patent Application Laid-Open No. 2004-266972. FIG. 3 in Japanese Patent Application Laid-Open No. 2004-266972 shows a specific configuration of a modulator. An up/down command of an inverter-side carrier is outputted based on an up/down signal of a carrier on a rectifier side and on an output pulse obtained by a PWM (pulse width modulation) on the rectifier side. However, in Japanese Patent Application Laid-Open No. 2004-266972, as apparent from FIG. 4 thereof, the same thing as that in Wei, L., Lipo, T. A., Chan, H, “Matrix Converter Topologies With Reduced Number of Switches,” PESC 2002, Jun. 23-27, 2002, vol. 1, pp 57-63. is merely shown as a result.
Note that, in FIG. 8 of Japanese Patent No. 4135026, a mode of modulating by the inverter and the converter using the same carrier is shown.
Fujita, Sakakibara, Matsuno, “Application and Development of the Three Phase Indirect Matrix Converter for Air Conditioners”, The papers of Joint Technical Meeting on Semiconductor Power Converter/Vehicle Technology/Home and Consumer Appliances, SPC-12-174NT-12-025/HCA-12-059, IEE Japan 2012(20), pp. 31-36, 2012 Dec. 6 shows that a modulation is realized by a microcomputer and an FPGA (Field-Programmable Gate Array).
Note that Japanese Patent Application Laid-Open No. 2011-193678, Renesas Electronics Application Note: RX62T Group—Usage Example of 12-Bit AD Converter in One Shunt Current Detection Method, R01AN0821JJ0100 and Renesas Electronics Application Note: RX62T-MTU3 Complementary PWM mode, R01AN0731JT0101, which are related to the present application, are listed in addition to the above.